Immediate and delayed placement of the intrauterine device after abortion: a systematic review and meta-analysis

This article aims to report the comprehensive and up-to-date analysis and evidence of the insertion rate, expulsion rate, removal rate, and utilization rate of immediate placement of intrauterine devices (IUDs) versus delayed placement after artificial abortion. PubMed, Embase, Cochrane, Web of Science, CNKI, and Wanfang databases were comprehensively searched up to January 12, 2024 for studies that compared immediate versus delayed insertion of IUDs after abortion. The evaluation metrics included the number of IUD insertion after surgical or medical abortions, the frequency of expulsion and removal at 6 months or 1 year, the number of continued usage, pain intensity scores, the number of infections, the duration of bleeding, and instances of uterine perforation during or after IUD insertion. Ten randomized controlled articles were eligible, comprising 11 research projects, of which 3 projects involved the placement of an IUD after surgical abortion, and 8 projects involved the placement of an IUD after medical abortion. This included 2025 patients (977 in the immediate insertion group and 1,048 in the delayed insertion group). We summarized all the extracted evidence. The meta-analysis results indicated that for post-surgical abortions, the immediate insertion group exhibited a higher IUD placement rate than the delayed insertion group. After medical abortions, the immediate insertion group showed higher rates of IUD placement, utilization, and expulsion at 6 months or 1 year. The two groups showed no statistically significant differences in the removal rate, post-insertion infection rate, pain scores during insertion, and days of bleeding during the follow-up period. Compared to delayed placement, immediate insertion of IUDs can not only increase the usage rate at 6 months or 1 year but also enhance the placement rate.


Inclusion and exclusion criteria
The following criteria were used to include studies: (1) study design: randomized controlled trials (RCTs), (2)  study population: adult females who underwent surgical or medical abortion and received IUD placement for contraception, (3) comparative studies of immediate (< 10 days after abortion) versus delayed insertion of IUDs (> 2 weeks after abortion), (4) surgical abortion is to extract the gestational sac through uterine aspiration, while medical abortion is to completely discharge the gestational sac using drugs (such as Mifepristone or Misoprostol); the gestational age at abortion involves early pregnancy abortion (gestational age 64-84 days) and mid-pregnancy abortion (gestational age 85-196 days) 13 , (5) at least one outcome measure was assessed, such as the successful insertion rate, expulsion rate, removal rate, pain scores during insertion, infection rate after IUD insertion, duration of post-insertion bleeding, retention rate at 6 months or 1 year, and other complications, and (6) with available and sufficient data of weighted mean difference (WMD), standardized mean difference (SMD), or to calculate relative risk (RR).
Duplicates, comments, case reports, reviews, meta-analyses, editorials, unpublished manuscripts, letters, conference abstracts, and articles not in English or Chinese were excluded.

Data extraction
Two reviewers independently extracted the data.Any disagreements were resolved by a third reviewer who made the final decision.The data extracted from the included studies were as follows: publication year, first author, study duration, country, registration number, sample size, study design, age, body mass index (BMI), gestational age at medical abortion (in days), past pregnancy(≥ 1), parity(≥ 1), prior abortion(≥ 1), number of successful IUD insertion (the IUD was inserted after the expulsion of the conception product in both the immediate and delayed groups), number of IUD expulsions and removals at 6 months or 1 year, number of IUD users at 6-months or 1-year follow-up, number of infections after insertion, pain scores during insertion, duration of post-insertion bleeding, and number of cases with uterine perforation.When continuous variables were reported as medians or interquartile ranges, a calculator that includes sample size was utilized to harmonize the varying data representations in the literature and the data were ultimately expressed as mean and standard deviation 14,15 .In cases of missing or unreported data in the studies, we attempted to contact the respective authors to acquire complete data, if available.

Quality assessment
The quality assessment of the eligible RCTs was performed in accordance with the Cochrane Handbook for Systematic Reviews of Interventions 5.1.0.The evaluation involved seven domains, including the blinding of participants and staff, the creation of random sequences, the blinding of outcome assessment, the concealment of allocations, the use of selective reporting, the use of incomplete outcome data, and additional sources of bias 16 .Each facet of the study was assessed for bias, classified as low, high, or unclear risk.Studies with a greater number of domains deemed "low risk" were regarded as higher quality.Two reviewers independently assessed the quality and level of evidence of the included studies, and any discrepancies were resolved through discussion.

Statistical analysis
Evidence synthesis was conducted using Review Manager 5.4 (Cochrane Collaboration, Oxford, UK).Furthermore, WMD and SMD were used as effect sizes for continuous variables, and RR for dichotomous variables.All effect sizes were reported with 95% confidence intervals (CIs).Moreover, the heterogeneity of the included studies www.nature.com/scientificreports/ was measured using the chi-square (C 2 ) test and quantified by the I-squared (I 2 ) statistic 17 .A C 2 p-value < 0.05 or I 2 > 50% was defined as significant heterogeneity.Due to heterogeneity across the studies, a random-effects model was adopted to combine WMD, SMD, or RR.
In view of the influence of abortion methods on the outcomes, we subgrouped the methods into surgical abortion and medical abortion for separate analyses.Based on different abortion methods, subgroup analyses were conducted according to gestational age, including early pregnancy abortion (gestational age 64-84 days) and mid-pregnancy abortion (gestational age 85-196 days).Subgroup analyses based on IUD type and region after medical abortion were also performed.The results are shown in Table 1.One-way sensitivity analyses were also conducted to assess the impact of the included studies on the overall outcomes, particularly in cases of significant heterogeneity, as depicted in Fig. 1.Funnel plots were created using Review Manager 5.4 to visually evaluate publication bias.Additionally, Egger's regression test 18 was implemented by using Stata 15.0 (Stata Corp, College Station, TX, USA) for outcomes reported in three or more included studies.For publication bias, a p-value of 0.05 or lower was interpreted as statistically significant.

Ethics approval
In accordance with local legislation and institutional requirements, this study did not require ethical review and approval of human subjects.

Literature search and study characteristics
The process of systematic search and selection is exhibited in Fig. 2. A total of 8750 articles were identified through systematic literature searches in PubMed (n = 1565), Embase (n = 988), Cochrane (n = 218), Web of  As the study by Korjamo et al. 24 assigned women requesting IUD placement after abortion into two groups based on gestational age (64-84 days and 85-140 days), we regarded it as two separate studies for analysis.Therefore, this meta-analysis included 11 RCTs.The quality assessment results of all eligible studies are provided in Fig. 3.The study characteristics, including the study period, location, sample size, specific timing of IUD placement, type of IUDs, and maximum follow-up duration are displayed in Table 2.

IUD inserted
Three studies showed successful IUD insertions (IUD inserted after the expulsion of the conception product) in participants after surgical abortion and eight studies after medical abortion.As for IUD insertion after surgical abortions, 878 patients were included (406 in the immediate placement group and 472 in the delayed placement group) 9,21,22 .The pooled analysis showed that the immediate placement group had a significantly higher rate of successful insertion than the delayed placement group (RR: 1.96; 95% CI 1.19, 3.21; P = 0.008), with significant heterogeneity (I 2 = 91%, P < 0.00001) (Fig. 4a).Visualization assessment via funnel plot showed no significant publication bias (Fig. 6a).Egger's test was not statistically significant (P = 0.061).Subgroup analysis by gestational week at abortion revealed P < 0.00001 in both groups.To identify the source of heterogeneity, we conducted a sensitivity analysis.The results were unstable; after excluding the data from the study by Hohmann et al., the statistical results became insignificant (Fig. 1a).Additionally, we determined the source of heterogeneity.By excluding the article by Bednarek et al., the heterogeneity decreased from 91 to 0%, suggesting that this might be the source of the heterogeneity.

IUD expelled
Three studies analyzed the 6-month expulsion rate of IUDs in 638 subjects who underwent surgical abortion (366 in the immediate placement group and 272 in the delayed placement group) 9,21,22 .The meta-analysis showed no difference in expulsion rates between the immediate and delayed placement groups (RR: 1.82; 95% CI 0.79, 4.21; P = 0.16), with no significant heterogeneity (I 2 = 0%, P = 0.96) (Fig. 4b).The funnel plot in Fig. 6b exhibits no discernible evidence of publication bias, and the results from Egger's test do not indicate a significant presence of publication bias (P = 0.744).Following subgrouping based on gestational weeks at abortion, the results also showed no significant statistical difference.
Six studies analyzed the expulsion rate of IUDs in 800 patients after medical abortion at 6 months or 1 year follow-up 19,[23][24][25][26] .Among them, five studies reported the expulsion rate of IUDs after medical abortion in early pregnancy (372 in the immediate placement group and 373 in the delayed placement group) 19,[23][24][25][26] .One study reported the expulsion rate of IUDs after medical abortion in mid-pregnancy (27 in the immediate placement group and 28 in the delayed placement group) 24 .The combined analysis showed that the expulsion rate in the immediate placement group was higher than that in the delayed placement group (RR: 2.08; 95% CI 1.42, 3.05; P = 0.0002), with no heterogeneity (I 2 = 0%, P = 0.69) (Fig. 5b).The funnel plot showed no apparent publication bias (Fig. 7b), and Egger's test did not reveal any substantial publication bias (P = 0.870).In the subgroup analysis by IUD type and region, one study conducted in the USA using only Cu-IUDs showed no statistically significant difference 26 (RR: 1.37; 95% CI 0.52, 3.59; P = 0.52).Similarly, one study using LNG-IUS or Cu-IUD observed no statistical significance 19 (RR: 1.31; 95% CI 0.39, 4.39; P = 0.67) (Table 1).

IUD removed
In the three studies 9,21,22 on IUD removal rates at 6 months after surgical abortion, no significant difference was noted in the combined results (RR: 1.27; 95% CI 0.65, 2.49; P = 0.49) (Fig. 4c).The funnel plot in Fig. 6c did not show any significant publication bias, and Egger's test also found no publication bias (P = 0.911).In six follow-up studies 19,[23][24][25][26] on the removal rates of IUDs 6 months or 1 year after medical abortions, five studies were for early pregnancy abortion groups (372 cases in the immediate placement group and 373 cases in the delayed placement group) 19,[23][24][25][26] , and one study was for mid-pregnancy abortion groups (27 cases in the immediate placement group and 28 cases in the delayed placement group) 24 .The combined results showed no marked difference in the IUD removal rates between the two groups (RR: 1.10; 95% CI 0.52, 2.31; P = 0.81), with no significant heterogeneity (I 2 = 35%, P = 0.18) (Fig. 5c).The funnel plot showed no obvious publication bias (Fig. 7c).Egger's test revealed no significant publication bias (P = 0.996).

IUD used
Three studies reported the number of IUD users at 6 months after surgical abortion, including 672 women (309 in the immediate group and 363 in the delayed group) 9,21,22 .The difference between the two groups was not statistically significant (RR: 1.66; 95% CI 0.87, 3.18; P = 0.12), with significant heterogeneity (I 2 = 93%, P < 0.00001) (Fig. 4d).The funnel plot showed no obvious publication bias (Fig. 6d).Egger's test did not find significant publication bias (P = 0.477).Our sensitivity analysis results were unstable.After excluding the article by Cremer et al. 21, the heterogeneity decreased from 93 to 0%, indicating this article may be the source of the heterogeneity (Fig. 1c).
Eight studies reported the number of IUD users at 6 months or 1 year after medical abortion, involving 1135 patients (565 in the immediate group and 570 in the delayed group) 8,19,20,[23][24][25][26] .The difference between the two groups was statistically significant (RR: 1.18; 95% CI 1.01, 1.39; P = 0.04).The immediate placement group had a higher usage rate at 6 months or 1 year than the delayed placement group, with considerable heterogeneity (I 2 = 74%, P = 0.0004) (Fig. 5d).The funnel plot showed no obvious publication bias (Fig. 7d).Egger's test did not find significant publication bias (P = 0.627).Subgroup analysis based on gestational weeks at abortion showed that, in the early pregnancy abortion group, the number of IUD users at 6 months or 1 year after medical abortion was higher in the immediate group than that in the delayed group, with significant differences (RR: 1.11; 95% CI 1.00, 1.22; P = 0.04) and insignificant heterogeneity (I 2 = 27%, P = 0.23) (Fig. 5d).In the mid-pregnancy abortion group, there was no statistically significant difference between the two groups (RR: 1.60; 95% CI 0.74, 3.45; P = 0.23), with significant heterogeneity (I 2 = 91%, P = 0.001).
Subgroup analyses based on IUD type and region displayed no statistically significant differences in the two studies 20,26 that exclusively used Cu-IUD (RR: 1.63; 95% CI 0.80, 3.29; P = 0.18).Similarly, there was no marked difference in the two studies 8,19 using either LNG-IUS or Cu-IUD (RR: 1.03; 95% CI 0.91, 1.15; P = 0.66).In two studies 20,26 conducted in Africa and the United States, as well as six combined studies 8,19,[23][24][25] in Europe, there were also no statistically significant differences in outcomes (Table 1).The sensitivity analysis revealed unstable results.After excluding the study by Constant et al. 20 , heterogeneity decreased to 12%, indicating that this study was a potential source of heterogeneity (Fig. 1d).

Infection
The combined results for infections after immediate versus delayed IUD insertion following surgical abortion showed no significant statistical difference (RR: 1.00; 95% CI 0.32, 3.13; P = 0.99) (Fig. 4e).www.nature.com/scientificreports/Following medical abortion, the combined results for infections after IUD insertion also showed no statistical difference (RR: 1.30; 95% CI 0.66, 2.56; P = 0.45).There was no statistical difference in the outcomes between the early pregnancy abortion group and the mid-pregnancy abortion group (Fig. 5e).The funnel plot showed visual publication bias (Fig. 7e).However, Egger's test found no statistical significance (P = 0.265), suggesting no apparent publication bias.

Pain score at IUD insertion (VAS or NRS) after medical abortion
In studies on pain scores after IUD insertion following medical abortion, 3 studies were included, with 391 patients (200 in the immediate group and 191 in the delayed group) 8,24,25 .The pooled evidence revealed no statistically significant difference between the immediate and delayed IUD placement groups (SMD − 0.15; 95% CI − 0.46, 0.15; P = 0.33), affirming the absence of significant differences in IUD insertion pain.However, notable heterogeneity was observed (I 2 = 52%, P = 0.13) (Fig. 5f).The funnel plot in Fig. 7f and Egger's test (P = 0.159) did not show significant publication bias.In subgroup analyses based on IUD type and region, one study 8 using LNG-IUS or Cu-IUD showed significant differences in pain scores (SMD: − 0.39; 95% CI − 0.65, − 0.12; P = 0.004) (Table 1).Our sensitivity analysis showed robust results.After excluding the article by Hogmark et al. 8 , heterogeneity decreased from 52 to 0%, suggesting that this study might be the source of the heterogeneity (Fig. 1e).

Uterine perforation
No severe adverse events like uterine perforation were observed in any of the included studies.

Discussion
IUDs are regarded as highly effective contraceptive devices when correctly inserted and used.They offer excellent protection against pregnancy with minimal systemic side effects 27,28 .Their effectiveness, safety, and satisfaction have been confirmed across various populations, including multiparous, nulliparous, and young women 29 .In the past few years, there has been ongoing research on the advantages and disadvantages of immediate post-abortion IUD placement versus delayed placement.This topic has generated controversy worldwide 10,30 .Therefore, we conducted this systematic review and meta-analysis, which revealed several important findings.Since the abortion method may significantly impact the outcomes of IUD placement, we analyzed the data separately for surgical abortions and medical abortions and made comparative analyses based on the gestational week at abortion.For surgical abortions, our combined data showed significantly higher IUD insertion rates in the immediate placement group than that in the delayed placement group.However, no statistically significant differences were noticed in IUD expulsion rate, removal rate, IUD usage rates after 6 months, or infection rate post-insertion, which may be related to the limited included studies.Previous studies have indicated that immediate IUD insertion following surgical abortion is safe and effective 31,32 , particularly in IUD insertion rates and usage rates, despite reports of higher expulsion rates.This method is still worth promoting 32 .Concerning medical abortion, we first found that the immediate placement group had a higher IUD insertion rate, especially in the early pregnancy abortion group.Meanwhile, the expulsion rates of IUDs after 6 months or 1 year after medical abortion were higher in the immediate placement group than in the delayed group, but the usage rates after 6 months or 1 year were relatively higher in the immediate group.Our results also showed no significant differences between the two groups in removal rates, infection rates, pain scores during insertion, and bleeding days post-insertion after 6 months or 1 year of medical abortion IUD placement.
Sensitivity and subgroup analyses were performed on results with heterogeneity to identify potential sources of heterogeneity.As for surgical abortion, due to the limited included studies, the results might be related to a higher rate of follow-up loss 20,21 .In the sensitivity analysis of medical abortions, the outcomes of post-abortion IUD placement were relatively robust, and the heterogeneity might be related to the influence of mid-trimester www.nature.com/scientificreports/abortions and the potential impact of contraceptive device type (Cu-IUD) as suggested by Constant et al. 20 .For the heterogeneity in pain scores after IUD insertion following medical abortions, the results of the sensitivity analysis were relatively robust.We also identified that heterogeneity may stem from the study of Hogmark et al. 8 , Science (n = 635), CNKI (n = 1768), and Wanfang database (n = 3576).After removing duplicates and papers published before 2003, the abstracts and titles of the remaining 2223 papers were reviewed.Finally, 10 full-text articles were included in the meta-analysis, involving 2025 patients (977 in the immediate placement group and 1,048 in the delayed placement group)8,9,[19][20][21][22][23][24][25][26] .All 10 articles were RCTs.

Figure 2 .
Figure 2. Flowchart of the systematic search and selection process.

Figure 3 .
Figure 3. Risk of bias graph and summary.

Figure 5 .
Figure 5. Forest plot based on medical abortion.(a) IUD inserted.(b) IUD expelled at 6 months or 1 year.(c) IUD removed at 6 months or 1 year.(d) IUD used at 6 months or 1 year.(e) Infection.(f) Pain score at IUD insertion (VAS or NRS).(g) Number of bleeding or spotting days during the reference period.

Figure 7 .
Figure 7. Funnel plot based on medical abortion.(a) IUD inserted.(b) IUD expelled at 6 months or 1 year.(c) IUD removed at 6 months or 1 year.(d) IUD used at 6 months or 1 year.(e) Infection.(f) Pain score at IUD insertion (VAS or NRS).(g) Number of bleeding or spotting days during the reference period.

Table 1 .
Subgroup analysis of intrauterine device use and adverse reactions after medical abortion.IUD intrauterine device, LNG-IUS levonorgestrel intrauterine system, Cu-IUD copper intrauterine device, RR relative risk, SMD standardized mean difference, CI confidence interval.

Table 2 .
Baseline characteristics of include studies and methodological assessment.RCT randomised controlled trial, LNG-IUS levonorgestrel intrauterine system, Cu-IUD copper intrauterine device, MTOP medical termination of pregnancy.

Table 3 .
Demographics and clinical characteristics of included studies.BMI body mass index, WMD weighted mean difference, RR relative risk, CI confidence interval.